Upcycling the Spent Mushroom Substrate of the Grey Oyster Mushroom Pleurotus pulmonarius as a Source of Lignocellulolytic Enzymes for Palm Oil Mill Effluent Hydrolysis

Abstract

Mushroom cultivation along with the palm oil industry in Malaysia have contributed to large volumes of accumulated lignocellulosic residues that cause serious environmental pollution when these agroresidues are burned. In this study, we illustrated the utilization of lignocellulolytic enzymes from the spent mushroom substrate of Pleurotus pulmonarius for the hydrolysis of palm oil mill effluent (POME). The hydrolysate was used for the production of biohydrogen gas and enzyme assays were carried out to determine the productivities/activities of lignin peroxidase, laccase, xylanase, endoglucanase and β-glucosidase in spent mushroom substrate. Further, the enzyme cocktails were concentrated for the hydrolysis of POME. Central composite design of response surface methodology was performed to examine the effects of enzyme loading, incubation time and pH on the reducing sugar yield. Productivities of the enzymes for xylanase, laccase, endoglucanase, lignin peroxidase and β-glucosidase were 2.3, 4.1, 14.6, 214.1, and 915.4 U g -1 , respectively. A maximum of 3.75 g/l of reducing sugar was obtained under optimized conditions of 15 h incubation time with 10% enzyme loading (v/v) at a pH of 4.8, which was consistent with the predicted reducing sugar concentration (3.76 g/l). The biohydrogen cumulative volume (302.78 ml H 2 .L -1 POME) and 83.52% biohydrogen gas were recorded using batch fermentation which indicated that the enzymes of spent mushroom substrate can be utilized for hydrolysis of POME.

Improved Performance of a Novel-Model Laccase Based Microbial Fuel Cell (LB-MFC) with Edible Mushroom as a Whole-Cell Biocatalyst

“…The novel model demonstrated the effective potential for future growth in bio-electricity generation. Pleurotus florida Wheat straw 301.58±2.95 [24] Pleurotus eryngii ND 1.33±0.33 [25] P. ostreatus ND 0.07±0.00 [26] P. pulmonarius ND 0.82±0.01 [27]…”

Spent substrate from mushroom cultivation: exploitation potential toward various applications and value-added products

“…Crude extracts of P. pulmonarius SMS demonstrated laccase and MnP activity [ 163 ]. P. pulmonarius SMS was also used to extract several hydrolases and oxidoreductases, and the extract was used for the hydrolysis of palm oil mill effluent to produce biohydrogen [ 176 ]. Extraction of xylanases from P. ostreatus and P. citrinopileatus SMS has also been investigated [ 177 ].…”